Layered Positive Electrode Composition for Battery Safety and Capacity

Solution Overview

Problem

Existing rechargeable lithium batteries face challenges in achieving high capacity and safety, particularly with lithium iron phosphate-based compounds, which have low lithium availability, and lithium cobalt-based oxides, which have low safety in cell bending tests.

Innovation Solution

A two-layer composite positive electrode active material layer is formed using a lithium iron phosphate-based compound and a lithium cobalt-based oxide, with a controlled weight ratio and particle size distribution to enhance safety and capacity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If lithium iron phosphate-based compound is used as positive electrode active material, then safety is improved, but capacity is reduced due to low lithium availability

Engineering Contradiction:

ImprovesafetyVSAvoidcapacity

Core Design Contradiction:

ReliabilityVSQuantity of substance

Solution Approach 1:

The patent combines lithium iron phosphate-based compound (providing safety) with lithium cobalt-based oxide (providing high capacity) in a composite positive electrode active material. This merging allows the battery to simultaneously achieve excellent safety characteristics and high capacity characteristics that neither material can provide alone.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The patent creates a composite material system by forming a positive electrode active material layer containing both lithium iron phosphate-based compound and lithium cobalt-based oxide. This composite structure enables the battery to exhibit both the safety advantages of lithium iron phosphate and the high capacity advantages of lithium cobalt-based oxide.

Inventive Principle:

Principle #40Composite materials

2Quantity of substance

If lithium cobalt-based oxide is used as positive electrode active material, then capacity is improved, but safety deteriorates in cell bending tests

Engineering Contradiction:

ImprovecapacityVSAvoidsafety

Core Design Contradiction:

Quantity of substanceVSReliability

Solution Approach 1:

The patent combines lithium iron phosphate-based compound (providing safety) with lithium cobalt-based oxide (providing high capacity) in a composite positive electrode active material. This merging allows the battery to simultaneously achieve excellent safety characteristics and high capacity characteristics that neither material can provide alone.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The patent creates a composite material system by forming a positive electrode active material layer containing both lithium iron phosphate-based compound and lithium cobalt-based oxide. This composite structure enables the battery to exhibit both the safety advantages of lithium iron phosphate and the high capacity advantages of lithium cobalt-based oxide.

Inventive Principle:

Principle #40Composite materials

3Productivity

If high energy density is pursued for electric vehicles and energy storage systems, then productivity and capacity are improved, but safety and structural integrity may deteriorate

Engineering Contradiction:

Improveenergy densityVSAvoidsafety

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The patent creates a composite material system by forming a positive electrode active material layer containing both lithium iron phosphate-based compound and lithium cobalt-based oxide. This composite structure enables the battery to exhibit both the safety advantages of lithium iron phosphate and the high capacity advantages of lithium cobalt-based oxide.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The patent optimizes the weight ratio of lithium cobalt-based oxide to lithium iron phosphate-based compound within 30:70 to 70:30 to achieve the best balance between safety and capacity characteristics, demonstrating parameter optimization to resolve the contradiction between energy density and safety.

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS20250349836A1Positive electrodes and rechargeable lithium batteries

Publication Date: 2025.11.13 SAMSUNG SDI CO LTD

AI summary

A positive electrode and a rechargeable lithium battery including the positive electrode are disclosed. The positive electrode may include a positive electrode current collector, a first positive electrode active material layer provided on the positive electrode current collector and including a first positive electrode active material, and a second positive electrode active material layer provided on the first positive electrode active material layer and including a second positive electrode active material, wherein the first positive electrode active material may include a lithium iron phosphate-based compound, the second positive electrode active material may include a lithium cobalt-based oxide, and a weight ratio of the second positive electrode active material to the first positive electrode active material may be about 40 to about 55.